How to Counterbore a Hole in Marble

I have marble countertops in the kitchen in our new construction home. The electrical code is requiring us to install two outlets in these countertops. I’d like to install Hubbell flush mount plugs shown in the photo below, but the installation requires a counterbored 0.09” hole into the marble top (also shown in photos below).

My fabricator says he doesn’t have the tools to do it and cannot do it. I’m thinking of doing it myself using my woodworking router, but with a diamond straight bit.

Can anyone shed some light on whether this will work or let me know how I can do this? I’m assuming once I’ve counterbored the hole, my fabricator could like use his normal method to cut the remaining inner hole (hole saw i suppose)

Interval (post #216079, reply #2 of 3)

Correct. I should have been more specific. The code doesn’t require it installed in the countertop but the interval is the issue. We have a large window that is behind this counter top and cannot put the outlets in the window. Therefore to comply with the interval, we need to put them in the counter top based on the inspector’s instruction.

See if he will allow you to (post #216079, reply #3 of 3)

Exception to (5): To comply with the conditions specified in
(1) or (2), receptacle outlets shall be permitted to be
mounted not more than 300 mm (12 in.) below the countertop.
Receptacles mounted below a countertop in accordance
with this exception shall not be located where the
countertop extends rnore than J 50 mm (6 in.) beyond its
support base.
( 1) Construction for the physically impaired

Tell him your wheelchair bound mother in law will be using the kitchen ;)